143 lines
4.2 KiB
Diff
143 lines
4.2 KiB
Diff
From a8ea42d2aa3738c680a932e2c42257ce4a880a47 Mon Sep 17 00:00:00 2001
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From: "Richard W.M. Jones" <rjones@redhat.com>
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Date: Tue, 10 Aug 2021 08:39:15 +0100
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Subject: [PATCH] delay: Fix delay-close
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See comments in the code for how this has been fixed.
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This only delays clients which use NBD_CMD_DISC (libnbd
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nbd_shutdown(3)). Clients which drop the connection obviously cannot
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be delayed. For example:
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$ nbdkit --filter=delay null delay-close=3 \
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--run 'time nbdsh -u $uri -c "h.shutdown()"
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time nbdsh -u $uri -c "pass"'
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real 0m3.061s # Client used shutdown, was delayed
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user 0m0.028s
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sys 0m0.030s
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real 0m0.058s # Client disconnected, was not delayed
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user 0m0.029s
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sys 0m0.027s
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Reported-by: Ming Xie
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Fixes: commit de8dcd3a34a38b088a0f9a6f8ca754702ad1f598
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Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1991652
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(cherry picked from commit 0cafebdb67d0d557ba1be8ea306b8acc5d9b2203)
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---
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filters/delay/delay.c | 42 +++++++++++++++++++--------
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filters/delay/nbdkit-delay-filter.pod | 14 +++++++--
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2 files changed, 41 insertions(+), 15 deletions(-)
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diff --git a/filters/delay/delay.c b/filters/delay/delay.c
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index df3729a7..9252b855 100644
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--- a/filters/delay/delay.c
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+++ b/filters/delay/delay.c
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@@ -39,6 +39,7 @@
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#include <stdbool.h>
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#include <errno.h>
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#include <limits.h>
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+#include <time.h>
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#include <nbdkit-filter.h>
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@@ -134,12 +135,6 @@ open_delay (int *err)
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return delay (delay_open_ms, err);
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}
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-static int
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-close_delay (int *err)
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-{
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- return delay (delay_close_ms, err);
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-}
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-
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/* Called for each key=value passed on the command line. */
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static int
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delay_config (nbdkit_next_config *next, nbdkit_backend *nxdata,
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@@ -253,13 +248,36 @@ delay_open (nbdkit_next_open *next, nbdkit_context *nxdata,
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return NBDKIT_HANDLE_NOT_NEEDED;
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}
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-/* Close connection. */
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-static void
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-delay_close (void *handle)
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+/* Close connection.
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+ *
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+ * We cannot call nbdkit_nanosleep here because the socket may have
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+ * been closed and that function will abort and return immediately.
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+ * However we want to force a sleep (even if the server is shutting
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+ * down) so use regular nanosleep instead.
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+ *
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+ * We cannot use the .close callback because that happens after the
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+ * socket has closed, thus not delaying the client. By using
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+ * .finalize we can delay well-behaved clients (those that use
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+ * NBD_CMD_DISC). We cannot delay clients that drop the connection.
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+ */
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+static int
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+delay_finalize (nbdkit_next *next, void *handle)
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{
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- int err;
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+ const unsigned ms = delay_close_ms;
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- close_delay (&err);
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+ if (ms > 0) {
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+ struct timespec ts;
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+
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+ ts.tv_sec = ms / 1000;
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+ ts.tv_nsec = (ms % 1000) * 1000000;
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+ /* If nanosleep fails we don't really want to interrupt the chain
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+ * of finalize calls through the other filters, so ignore any
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+ * error here.
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+ */
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+ nanosleep (&ts, NULL);
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+ }
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+
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+ return next->finalize (next);
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}
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/* Read data. */
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@@ -340,7 +358,7 @@ static struct nbdkit_filter filter = {
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.config_help = delay_config_help,
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.can_fast_zero = delay_can_fast_zero,
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.open = delay_open,
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- .close = delay_close,
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+ .finalize = delay_finalize,
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.pread = delay_pread,
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.pwrite = delay_pwrite,
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.zero = delay_zero,
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diff --git a/filters/delay/nbdkit-delay-filter.pod b/filters/delay/nbdkit-delay-filter.pod
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index 11ae544b..76614736 100644
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--- a/filters/delay/nbdkit-delay-filter.pod
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+++ b/filters/delay/nbdkit-delay-filter.pod
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@@ -117,15 +117,23 @@ the plugin.
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=item B<delay-open=>NNB<ms>
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+(nbdkit E<ge> 1.28)
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+
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+Delay open (client connection) by C<SECS> seconds or C<NN>
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+milliseconds.
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+
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=item B<delay-close=>SECS
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=item B<delay-close=>NNB<ms>
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(nbdkit E<ge> 1.28)
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-Delay open and close operations by C<SECS> seconds or C<NN>
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-milliseconds. Open corresponds to client connection. Close may not
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-be visible to clients if they abruptly disconnect.
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+Delay close (client disconnection) by C<SECS> seconds or C<NN>
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+milliseconds. This can also cause server shutdown to be delayed if
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+clients are connected at the time. This only affects clients that
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+gracefully disconnect (using C<NBD_CMD_DISC> / libnbd function
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+L<nbd_shutdown(3)>). Clients that abruptly disconnect from the server
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+cannot be delayed.
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=back
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--
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2.31.1
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